Sources said that the commission has received complaints of booth jamming from some areas. After verification, it was found that some complaints were true, the sources said.

Polling was held up for some time in 20 booths, including 18 in KMC area due to problems in the electronic voting machines, the sources said.

Despite allegations of violence by the opposition Trinamool Congress, the Bharatiya Janata Party and Congress, the police onlyconfirmed that a bomb had been thrown at a booth in north Kolkata, but polling was not affected.

Tension ran high in Kolkata's satellite town of Bidhannagar, where Communist Party of India-Marxist member of Parliament from Dum Dum Amitava Nandi threatened to withdraw party candidates alleging police excesses in the area.

CPI-M state secretary Anil Biswas, however, said that the police were doing their duty and there was no question of withdrawing any party nominee.

CPI-M politburo member Jyoti Basu, who cast his vote at Bidhannagar, said polling was peaceful.